It is known in the automobile and other industries that a fastener, such as a threaded stud or a nut can be welded to a sheet metal panel or other member. The fastener has multiple projections formed on the surface that will be welded to the panel. An electrode is applied to the fastener and a back up electrode is applied to the panel. Electric resistance weld current is conducted through the electrodes and is concentrated through the projections creating electric resistance welds between the projections and the panel.
In many applications, the panel will have an aperture that aligns with the fastener. In the case of a threaded stud, the threaded stud may extend through the aperture. In the case of the fastener being a nut, a bolt that will be eventually threaded into the nut can reach through the aperture. In either case, the projections formed on the fastener will typically leave a small gap between the base of the fastener and the panel. It is desirable to seal this small gap to prevent the passage of noise or liquid or gaseous matter.